Compensating or differential pressure or temperature responsive mechanism



July 8, 1958 E. D. HAIGLER 2,841,985 COMPENSATING OR DIFFERENTIAL PRESSURE OR TEMPERATURE RESPONSIVE MECHANISM Filed Sept. 8, 1953 INVENTOR.

United States Patent a.;

l COMPENSATING UR DFFERENTIAL PRESSURE OR TEMPERTRESlNSt/E HEECHANISM Edmund D. tliaigler, Hath-oro, Pa., assigner to Fischer Porter ompany, ltlatboro, Pa., a` corporation of Pennn Sylvania ApplicntionfSeptember 8, 1953, Serial'lalo. 378,9i5

4 Claims.. (Cl. I3-412) ydouble Bourdon-spring mounting Vof low friction, iny that essentially single-.point pivotsare used both forlow friction and to avoid the need for precision in the axial and angular alignments.

Itis another object of this invention to` provide these characteristics in a Bourdon tube mountinginterchangeable with the single `Bourdon mounting of my cfa-pending application Serial No. 378,943 4filed of even date herewith.

It is also an object of this invention to utilize the same over-range stops, the same Bourdon .tubes andmany other "parts iu common to the mechanism hereof and the mechanism of my cofpending application Serial'No. 378,943.

For the purpose of illustrating the present invention, vthere `are shown in the accompanyingvdrawings av form thereof which is at present preferred, although it is to be understood that thelvarious instrumentalities of which the invention consists can be variously -arranged and organ- `izedzandthatrthe invention is not limited to the precise arrangements t andsorganizations of i the `instrumentalities as therein `shownand described.

T he gures of the drawings, wherein like reference-nurnerals indicate like parts, are asfollows:

`Figure `1 represents a plan view'lofredouble-spring` Bourdon mechanism illustrating `oneembodiment of the `present invention.

Figure 2 represents a side elevation of `the same mechanism, partly in section.

Figure 3represents a plan view of the base.

Figure 4 represents a cross-sectional view, on an enlarged scale, of the right post assembly or measurement post assembly, which is disposed within the measuring Bourdon spring 140m, the uppermost or output-lever (160) portion of which is taken `on line daz- 4a of Figure 1, the Vnext portion of which (namely, through the overtravel mechanism and stop-mechanism) is taken on line Lily-4b of Figure rl, whilethe'lower portion of which is taken online -4c--4c of Figure 1.

Figure 5 represents a similar cross-sectional View, on

an lenlarged scale, of the left post assembly or compensat-V ing post assemblywhich is withinthe compensating Bourclon spring lllqtheupper portion of which is taken on line Sa-Sa of Figure l and the lower portion of which `is taken on line SI1-5b of Figure `l.

t Figure6 `represents a planview ofthe lower pivoted arm `303C (with itslmicroinetersslide) `of thetcompensating `on an instrument panel or on an instrument case. base 101'also includes holes Him and 111C, each counas at `123, and on this reduced-diameter supporting member 124 shown di; assembly shown in Figure 5 and onthe left side ofFigures l and 2.

Figure 7 represents a section ou line 5cl-5a of Figure l,of\the connection, to the compensating Bourdon-spring C, of the upper stationary anchorage arm 147 and the two capillary tubes 306e and il-Silc `which enter said Bourdon spring atits upper end.

Figure 8 represents a section on line lb-4b of Figure 1,\showing the connection between the upper end of the measuring Bourdon spring 140m and the movable arm 194 at the top of the post shown in Figure 4, and including the two capillary tubes 306m and m which are connected to the upper end of the Bourdon tube Mdm.

` Many of the parts of the compensating or ditferential pressure-or temperature measuring mechanism of the pressent application are also shown and described in co-pending application Serial No. 378,943 covering singledourdon-spring mountings and mechanisms.

The base 101 (Figure 3) is provided with countersunk holes 110, through which mountingscrews (shown in Figure l) may be extended, for mounting the mechanism The tersunkfrom beneath or on the under-side of the base i101, for receiving the screws 122m and 122e, respectively, by which the posts lldm and 11de are mounted `on the base 101, as indicated more particularly in Figures 2, 4 and 5.

Throughout this description, where a similar part, `element or component is provided both in or for the measurement-spring assembly as well as in or for the 4cornpeusating-spring assembly, the two elements are des* ignated by the same reference-numerah differentiated by the suffix-letters m and 0, respectively, m referring tothe measurement side and "c to the compensating side of the mechanism. This use of the same reference-.numerals, differentiated by letters m and c, is also used where the parts are not identical but similar and perform somewhatlsimilar functions, as, for instance, the posts '114m and 11d-c. Moreover, where the same descriptive Y matter applies equally to both m suflixed part and the c suixed part, the reference-numeral is used without either suffix; and such use is intended to cover both the m suixed and the c suilixed part bearing that reference-numeral.

The lower ends of the posts Eil/t are preferably slightly reduced in diameterg'fora short distance, as at M5, and such reduced ends 115 are recessed into the base 1M, as indicatedparticularly in Figures 4 and 5, so tol obtain rm'- er anchorage and rigidly between the base and said posts.

'The upper end of the post Mdm is reduced in diameter portion the stopparticularly in Figures 11-an`d 13 of copending application Serial No. 378,943 and also shown in Figures l, 2 and 4 lof the present application, is mounted, and secured in place by the setscrew 133. To this stop-supporting member E24, the stop-members 13d are adjustably secured (in anguar respect), by the set-screws Ml, so as to bring the stop- `edges 1h38 (Figures l and 4) at the proper distance from each other, according to the pointer-travel desired or according to the `travel desired for the output-arm intl ot" the mechanism.

A pivot pin 12d is mounted on top of the post 114m, coaxially therewith, by being set into an axial hole 1253 therein, and secured therein by the set-screw 12S. Upon the pivot-pin 126, a tubular bearing assembly lil is telescopieaily mounted as indicated particularly Figures l and 4; said tubular bearing assembly member 151 having its inner bore 153 slightly larger than the outer diameter of the pivot-pin l126, so that it clears the pivot pin at all times except `when it is slightly cocked. When slightly ner bore 153 of the tube 151 to limit the cocking. The

vlower end of the tubular bearing member 151 is enlarged, as indicated particularly in Figure 4, to form a spoollike lower portion including ilanges 202 (Figure 4) between which the coils of the spring 201 are disposed. In the lowermost portion of the tubular member 151, a short bearing 154 is provided, journaled on the pin 126, as indicated in Figure 4.

The driven lever or arm 196, having an up-turned coupling-lug 139 and a down-turned stop-finger 172, is mounted lon the tubular member 151, against the upper ange 202, and is soldered, brazed or otherwise afiixed thereto. The stop-finger 172 extends down, between the twostop-edges 138 of the two angularly adjustable stop members 134, so as to limit the angular motion of the tubular bearing-assembly member 151 and of the outputarm 160 secured thereto.

Superimposed upon the driven-lever 196, is the drivinglever 194- journaled on the outer surface of the tubular member 151, as indicated particularly in Figure 4, and is retained, against axial displacement, by the split lockingspring washer 197 engaging in an annular groove in the tubular member 151, as indicated in Figure 4. To the left end of the driving-lever 194 the Bourdon-tube-tip 148 is secured, by soldering, or the like (Figures l, 2, 4 and 8).

The coupling-member 139 is so disposed that when the Bourdon spring 140m expands, the end of the lever 194 which is juxtaposed to the coupling member 139 will move in a direction away from the coupling member 139. The spring 201, having hooked ends 203 engaging oppositejends of the driving-lever 194 and of the drivenlever 196, as shown in Figures 2 and 4 (and also in Figures to 20, inclusive,rof co-pending application Serial No. 378,943), forms a resilient driving connection between the driving-lever 194 and the driven-lever 196, through which the upper or output end of the measuring Bourdon spring 140m yiedably drives the driven-lever 196 and hence the tubular bearing member 151 and output arm 1 secured thereto, when said Bourdon spring 140m expands. The driven-lever 196, bearing member 151, and output arm 160 come to a stop however when the stop-arm 172 meets the stop-edge 138 (Figure 4), while the driving-lever 194 and the upper output end of the Bourdon Springl140m can travel further or overtravel, because of the resilient connection between the driving and driven members provided by the spring 201.

The output-arm 160, its securement to the tubular bearing-member 151, and the micrometer slide 169 thereon, are the same as the corresponding elements in copending application Serial No. 378,943.

Into the upper end of the Bourdon spring 140m, preferably immediately below the portion of the tip 148 which is inserted into the end of the spring 140m, the two capillary tubes 306111 and 180m are inserted and soldered in place, to form fluid connection with the interior thereof. The capillary tube 306m extends from beneath the tip 148 in a spiral coil (also designated as 306m in Figures l and 2), and is finally fastened beneath the clip 182 held by screw 143 (Figure l), and then, through a reservelength coil 181m, this capillary is extended to and connected with the measuring bulb or other fluid-filled temperature-sensing or pressure-sensing element (not shown) located at the point of measurement. The capillary 180m extends from the top of the Bourdon-spring 140m, downwardly (within said spring), as indicated particularly in Figures l and 2, and terminates near the bottom of the spring 140m in a coupling-sleeve or closure-sleeve 116m as indicated in Figures l and 2, the outer end of which is closed in normal operation, but which may be opened to ll the Bourdon-spring 140m and its associated bulb or other measurement-sensing element or to adjust the setting thereof by varying the fluid content thereof, The lower end of the Bourdon-spring 140m is closed by the tip or anchorage member 248m, which is telesooped into and soldered into, in sealed relation, in the lower end of fit) the Bourdon-spring m. The outer or free end of the tip 248m is then soldered or otherwise affixed to the vertical portion 304m of the pivotal Bourdon-supporting arm 303m shown in Figures l, 2 and 4. The inner horizonal portion of the Bourdon-supporting arm 303m is provided with a journal-hole 254m at its inner end, which extends into a slot 301m in the post 114m, where it is pivoted or journaled on the pivot-pin 226m, which pin is tted neatly into the aligned holes 225m and is held therein by having its outer end abutting the inner end of the post-securing screw 122m (as shown particularly in Figure 4). A pair of thrust-washers 305m are placed on the pin 226m below and above the pivoted end of the Bourdon-supporting arm 303m, sol as to reduce the contact-area between the pivoted end of the arm 303m and the sides of the slot 301m. The slot 301m is made wide enough, so that the arm 303m can adjust itself, in an axial direction. lf the mechanism is mounted in the instrument-case or on the instrument-panel with the two axes of the posts 114 disposed vertically, then the Bourdon-supporting arm 303m will rest on the lower washer 305m (Figure 4), while if the mechanism is mounted with said post-axes disposed horizontally, then the arm 303m may iloat so that neither washer 305m bears against the side wall of the slot 301m, or the upper washer 305m may bear against the upper Vside of the slot 301m.

The proportions and adjustments are so made that when the arm 303m rests on the lower washer 305m, then the lowermost end of the bearing member 151 will still be just short of contacting the top of the reduceddiameter portion 123 of the post 114m, so that `the bearing member151 will still be oated, axially, while deriving its radial support through the short bearing 154.

The compensating Bourdon-spring 140e derives its main support by having its fixed anchorage member or tip secured to the upper stationary Bourdon-supporting 'arm 147 iixed to the upper end of the post 114C, as indicated in Figures l, 2 and 5. Thus, the Bourdon-tip 175 is soldered into the upper end of the compensating Bourdon-spring 140e, along with the capillary tubes 306C and e, as indicated in Figures 1, 2, 5 and 7. The capillary tube v306C extends downwardly from Vtheupper end of the Bourdon-spring 140C, in the spiral 306C shown particularly in Figures l and 2, and nally extends beneath the clip 183 and, through the spare-length coil l181C thereof, to the sleeve 179C through which it is closed oi or through which it may be connected to the compensating bulb or to a suitable length of compensated capillary tubing. Thus, the capillary tube 306C is of a length such that it Will provide adequate compensation for changes of temperature within the instrument-case or the temperature of the `air around the instrument-panel. If desired to compensate for changes in temperature along the path of travel of the capillary tube 306m which leads from the measuring Bourdon-spring 140m to the remgtelylocated sensing element, then the capillary tube 306e may be extended along this path, generally alongside of the capillary 306m, and then closed off just short of the point of measurement or the zone of measurement. In this manner changes in temperature outside the point of measurement may be compensated for. Moreover, if desired, temperature-differences or pressure-differences may in like manner be indicated by the mechanism of the present invention, by providing a bulb or other ternperature-sensing or pressure-sensing uid-iilled element at the end of the capillary 306C, located at a second point of measurement (diierent from the point of measurement to which the capillary 306m extends), and in this manner the mechanism of the present invention may be used to indicate, through the output-arm 160 thereof, the difference between or the summation of the two measurements; according to the manner in which the lower ends of the two Bourdon-springs (140m and'140c) are connected through the arms .303C and 303m, by means of the connecting-,rod or link 300,.,narnely, whether they are additively connected or subtractively connected.

The capillaryi180c extends down -from the Vtop of the Bourdon-spring 140C, in a manner `similarto theicapillary 180m, above referred to, and is used for the same purposes.

The mounting-hole in the stationary arm 147, through which the mounting-screw 222y extends, is preferably made oversize-in relation to the mounting-screw `222, so that the arm 147 can be laterally. adjusted `so as generally to place the Bourdon spring 140C in coaxial relation to the upper end ofthe postv114c. A washer 3M beneath the head of the screw Z22 serves more firmly to clamp the arm 14"/ in `its adjusted position when the screw 222 is tightened in the tapped hole `221 which extends down into the post 114C, axially.

The lower end 'of the Bourdon-spring 140C has the tip or anchorage member248c extended thereinto and soltiered in place, to close this end ofthe Bourdon-spring. The outer projecting or free end of the anchorage member or tip 248e is soldered to the vertical or off-setting portion 304C of the Bourdon-supporting pivot-arm 303C, as indicated in Figures 2 and 5. The inner end of the Bourdon-supporting arm 303e (Figures 5 and 6) has a journal-hole 254e and extends into the slot 301C and is journaled on the pivot-pin 226C, in a manner similar to the corresponding portions of the measurement-assembly. The single thrust-bearing washer 305C is suiicient here (Figure 5) because the Bourdon spring 140e` is supported from above, on the stationary arm 147, and is so adjusted that it doesnotever contact the upper sidewall ofthe slot 301C, and maj/even oattclear of the washer 305C.

To thelower,.outer,.horizontal portion of the Bourdonpivoting arm 303e, a micrometer adjusting mechanism is secured, by soldering or otherwise, similar to the micrometer arrangement on the output-arm 160, having a slider 169e with a pair of alternate link-pivot holes 17de, into one of which the pivotal end of the link or connecting rod 300 is operatively connected. The other end of the same link 300 is correspondingly connected into one of the pivot-holes 170m of the arm 303m (Figures l, 2, 5 and 4).

By the connection indicated in Figures l and 2, the two Bourdon-springs 140C and 140m are subtractively connected. Thus, with the two Bourdon-springs wound in the same direction, any expansion of the Bourdonspring 140e will move the lower or reference-end of the Bourdon-spring 140m in such a direction as to decrease the reading or measurement-indication supplied by the upper end of the Bourdon spring 140m to the output-arm 160.

By turning one or the other of the posts, 114e or 114m, 180 (about its axis), and so fastening it to the base lill, and then placing the corresponding Bourdonpivoting arm 303 also 180 about the axis of the post, and then re-connecting the two arms 303 through the link 360, which will now extend diagonally between the two post-axes, the two Bourdon springs will be connected additively. Such a reversal of effect of the tube 140s upon the base-reference-position of the lower end of the Bourdon spring 140m, can also be eiected by winding one or the other of the Bourdon springs in the opposite direction from the other. However, using identically wound springs, it is only necessary that the line of the link 300 not pass between the post-axes for subtractive connection or that it pass between the axes for an additive connection.

in this manner, the mechanism of the present invention may be used to indicate the sum of the two measurements or the difference of the two measurements (of either temperature pressure). To effect the summation of the two measurements, the expansive movements of the two Bourdon springs are connected to apply their motions in the same directions so` that both their motions will operate in thesame direction upon the output-arm 160. To eiect the subtraction of onemeasurement from the other, they are connected so thatthe expansive-motion of one spring is` subtracted fromthe expansive-motion of the other spring (as shown in Figures l and 2).

Similarly, the sum of or the differencebetween one Bourdon-motion proportional to pressure and one Bourdon-motion proportionalto temperature, may be measured by the mechanism of the present invention, by connecting one Bourdon-spring to apressure-sensing element (through its capillary tube 366) and connecting the otherV Bourdon-spring 140through a temperature-sensing element (throughits capillary tube 306), with or without a bi-metal compensator intervening one end of the temperature-responsive Bourdon spring and its corresponding anchorage `or support (in the manner shown and described in copending application Serial No. 378,943).

Ir" desiredVinstead of having one end of one of the Bourdon springs Mtl, as, for instance, the upper end ot" theBourdon spring 140e, stationarily fixed (as hereinabove indicated), this end may likewise be pivotally mounted, and connected to the measurement-motion of. another measurement-mechanism, so that the measurement-motion supplied by such other measurement-mechanism will pass through both Bourdon springs 140e and 140m, so that a composite measurement is delivered to the output-arm which represents the motions imparted by the two Bourdon'springs 140C and 140m (additively or subtractively)superimposed upon the measurement-motion of `such other measurement-mechanism, which is put into the upper end of the Bourdon spring 140e.

Where both ends of both Bourdon springs 140e and 140m are pivotally mounted and are floatedf it is desirable to supply fiexure-springs on the ends of the connecting-link 3h0, or to form the link 390 as a single flexure-strip pivotally connected to holes 17de and 170m, so as to get a more accurate connection and to eliminate any back-lash; the ends of such flexure-strip being pivotally connected to the holes e and 17tbm by neatfitting pivots. The lleXure-strip permits vertical or axial motions between the ends of the two Bourdon springs which are so connected by such exure-strip.

The present invention may be embodied in other specie forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the r present embodiment be considered in all respects as illustrative and not restrictive, reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

Having described the invention, the following is claimed:

l. A multiple Bourdon mechanism, including a base, a pair of stationary Bourdon-supporting posts extending from said base, a helical Bourdon tube disposed about one of said posts with one end thereof xedly secured thereto, an angularly displaceable anchorage for the other end of said tube pivotally mounted on said post at a point therealong in close proximity to the plane in which the other end of said Bourdon tube lies, said angularly displaceable anchorage member having its axis of pivotation substantially in the axis of said Bourdon tube, another helical Bourdon tube disposed about the other post with each Aof its ends movably mounted by being secured to corresponding angularly displaceable anchorage members pivotally mounted upon said post with their axes of pivotation coincidental with each other and with the axis of said Bourdon tube, said Bourdon tube having one of its ends in operative juxtaposition to the movable end of said iirst-mentioned Bourdon tube, means interconnecting the movable end of said first-mentioned Bourdon tube with the juxtaposed end of said last-mentioned Bourdon tube, thereby to set the so-connected end of said last-mentioned -.Bourdon tube by the response of said first-mentioned .Bourdon tube having each of its two ends movablymounted and arranged to move in an arcuate path generally about the same axis, a separate radial anchorage member for each of said ends, to which said ends are affixed, respectively, each of said anchorage members being pivoted co-axially in relation to each other, with the point of pivotation of each being in close proximity to the plane of the end of the Bourdon tube ailixed thereto, a second helical Bourdon tubel having its axis generally parallel to and spaced from the axis of the first-mentioned Bourdon tube and having one end thereof stationarily anchored and having its'other end in juxtaposition t0 one of the ends of the rst-mentioned Bourdon tube affixed to a pivoted anchorage member whose axis is gen erally coincident with the axis of said last-mentioned Bourdon tube, ,and means interconnecting the free end f of said last-mentioned Bourdon tube with the juxtaposed free end of said first-mentioned Bourdon tube, both connected ends of said interconnecting means being generally in the same plane and in close proximity to the connected ends of said two Bourdon tubes.

3. A multiple Bourdon tube mechanism, including two helical Bourdon tubes with theirtaxes spaced apart in a direction transversely thereof, one of said Bourdon tubes having each of its two ends movably mounted and arranged to move in an arcuate path generally about the.

axis thereof, and a separate radial anchorage member for each of said ends of said tube, to which of said tubeends, respectively, are aiiixed, each of said anchorage members being pivoted generally co-axially in relation to each other and to said Bourdon tube, the other of said:

Bourdon tubes having at least one of its ends movably mounted and arranged to move in an arcuatepath generally about the axis thereof, a radial anchorage member for said movable end of said last-mentioned Bourdon tube,

Vto which said tube-end is axed, said last-mentioned anchorage member being pivoted generally co-axially in relation to said last-mentioned Bourdon tube, said movably mounted end ofsaid last-mentioned Bourdon tube ,being disposed in operative juxtaposition to one of the ends of said first-mentioned Bourdon tube, and means interconnecting said juxtaposed movable ends of said two Bourdon tubes, whereby a movement of said movable end of said last-mentioned Bourdon tube determines the setting for said juxtaposed connected end of said rst-mentioned Bourdon tube.

4. A helical Bourdon tube mechanism, including a helical Bourdon tube, a stationary pivot member disposed within the helix of said Bourdon tube and having two pivots generally co-axial with the helix of said tube, one of said pivots being in juxtaposition to one of the ends of said tube and the other pivot being in juxtaposition to the other end of said tube, a generally radial tube-anchorage member pivoted on one of said pivots and having the juxtaposed end of said Bourdon tube affixed thereto, a generally radial tube-anchorage member pivoted on the other of said pivots and having the juxtaposed end of said tube afxed thereto, said tube-ends being arranged to be movable in arcuate paths generally about the axis of said helical Bourdon tube.

References Cited in the le of this patent UNITED STATES PATENTS 1,188,615 Goodyear etal June 27, 1916 1,307,037 Bristol June 17, 1919 2,375,300 Hubbard et al May 8, 1945 

